Upgrade xstream to 1.4.21 for CVE-2024-47072

[CraigAtInstrumental]

Expected behavior

There is a high vulnerability in xstream link.
It is fixed in 1.4.21.

Actual behavior

N/A

Steps to reproduce the problem

N/A

JMeter Version

5.6.3

Java Version

openjdk version "17.0.13" 2024-10-15

OS Version

Linux station-dev-2 6.8.0-50-generic #51~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Nov 21 12:03:03 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

[CraigAtInstrumental]

Added PR:here

[vlsi]

Fixed in #6431